Glazing and method of its production

ABSTRACT

The present document discloses a glazing in the form of a window glass or vehicle glass which comprises a transparent glass substrate, and a coating, which comprises at least one functional metal Ag alloy coating layer. The alloy coating layer consists essentially of Ag with an alloying agent selected from a group consisting of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Zr, Nb, Mo, In, Sn, Hf, Ta or W. An alloying agent concentration is 0.15-1.35 at. %, preferably 0.20-1.00 at. % or 0.25-0.80 at. % of the Ag alloy coating layer, the rest being Ag, and the Ag alloy coating layer has a thickness of 5-20 nm, preferably 8-15 nm or more preferably 8-12 nm.

TECHNICAL FIELD

The present disclosure relates to a glazing for use as window glass orvehicle glass and a method of producing a glazing.

BACKGROUND

Glazings with a high visible transmittance and high infrared (IR)reflectance are desirable in many applications, allowing visible lightto pass through the glazing while reflecting IR radiation to reduce heattransfer through the glazing.

Common types of glazings that are used in architectural applicationsinclude clear and tinted float glass, tempered glass, laminated glass aswell as a variety of coated glasses, all of which can be glazed singlyor as double, or even triple, glazing units.

It is known to provide coatings on window glass in order to reduce theamount of heat that is transferred through the glass. The most efficienttype of coating comprises at least one functional metal layer, whichtypically is made of silver (Ag) owing to its high IR reflectivitycharacteristics.

The functional metal layer is deposited between anti-reflective layerswhich each typically include at least one dielectric layer for tuningthe optical properties of the glazing. These anti-reflective layers alsoensure the protection of the functional metal layer from chemical attackand/or mechanical stress.

The optical and electrical properties of the glazing are directlyrelated to the quality of the functional metal layer in terms of, e.g.,crystallinity, grain size and interfacial roughness.

US 2006/0255727 A1 is related to a thin film reflector and transparentelectrical conductor for use as, e.g., window coating, comprising atransparent substrate coated with a stack of layers comprising afunctional metal layer of a Ag alloy.

US 2013/00118673 A1 discloses a glazing having a coating stack which mayinclude an IR reflecting layer formed of Ag or Ag alloy, and that aparticular range of alloying agent concentrations may help the Agmaintain the desirable optical characteristics of the Ag layer whileenhancing chemical, corrosion and/or mechanical durability.

A particular challenge is to increase reflectance of rays in the longwavelength IR part of the spectrum, such as 5-50 μm, while maintaininghigh transmission of light in the visible spectrum, such as 380-780 nm.Yet another challenge is to increase reflectance in the near IR part ofthe spectrum, such as 780-2500 nm, while maintaining high transmissionof light in the visible spectrum, such as 380-780 nm.

SUMMARY

It is an object of the present disclosure to provide a glazing for useas window glass or vehicle glass.

A further object is to provide a method of producing a glazing.

The invention is defined by the appended independent claims. Embodimentsare set forth in the dependent claims, in the following description andin the drawings.

According to a first aspect there is provided a glazing in the form of awindow glass or vehicle glass. The glazing comprises a transparent glasssubstrate and a coating. The coating comprises at least one functionalmetal Ag alloy coating layer. The Ag alloy coating layer consistsessentially of Ag with an alloying agent selected from a groupconsisting of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Zr, Nb,Mo, In, Sn, Hf, Ta or W. An alloying agent concentration is 0.15-1.35at. %, preferably 0.20-1.00 at. % or 0.25-0.80 at. % of the Ag alloycoating layer, the rest being Ag, and the Ag alloy coating layer has athickness of 5-20 nm, preferably 8-15 nm or more preferably 8-12 nm.

By “glazing” is herein meant a transparent substrate coated with a stackof thin film materials or layers.

The glazing can be used as a glass component of a building's facade orinternal surfaces (such as the glass panes in an insulated glass unit),and is also used to refer to the glass used in transport and utilityvehicles (such as windshields and panoramic roofs).

The glazing may be transparent. By transparent is herein meant a glazinghaving visible light transmission typically of the order of 20-85%.

The glazing may be a sheet. Such a sheet may be planar, single curved ordouble curved.

By window glass is herein meant a window glass for a building. It mayalso be a roof glass, glass facade or a door glass.

By vehicle glass is meant a glass for a vehicle, for example a rearglass, side glass, sun roof, windshield or a windscreen (front window)in a car.

By transparent substrate is here meant a substrate having visible lighttransmission typically of the order of 30-90%.

The transparent substrate may be substantially planar.

By “consists essentially of” is herein meant that the Ag alloy coatinglayer consists essentially of, or consists of, Ag and an alloying agent.The Ag alloy coating layer contains substantially only elemental silver,and the alloying agent and does not contain substantial amounts ofsilver compounds, but may contain insubstantial or incidental amounts ofimpurities ordinarily associated with silver and may also containincidental insubstantial or substantial amounts of materials that do notmaterially affect the basic and novel characteristics of the Ag alloycoating layer.

As a non-limiting example, the Ag alloy coating layer may contain lessthan 0.1 wt. %, preferably less than 0.05 wt. %, most preferably lessthan 0.01 wt. % of other components, such as incidental impurites.

The alloying agent concentration is herein calculated as a ratio of thealloying agent to the sum of the amounts of the silver and the alloyingagent. This means that possible incidental impurities are not includedin the alloying agent concentration.

The layers of the coating may, but need not, form a continuous layeronto the layer it is deposited upon or substrate.

The optical properties and the electrical properties of the glazing aredirectly related to the quality of the functional metal layer in termsof, e.g., crystallinity, grain size and interfacial roughness.

Experimental data discussed in the following description show that thecoating of the glazing, where the functional Ag metal alloy layer hasalloying agent concentrations in the interval above, has improvedcharacteristics in terms of lower sheet resistance as compared to acoating with an unalloyed Ag functional metal layer.

This is surprising, in view of the fact that US 2013/0118673 A1discloses a potential to merely maintainthe desirable opticalproperties.

The glazing may present a direct solar transmittance, as determinedaccording to the European standard EN 410, which is lower than a directsolar transmittance of a glazing having a coating with the same layerstructure and layer thicknesses as the Ag alloy coating layer, butwherein the functional metal Ag alloy coating layer is replaced by anunalloyed Ag functional metal layer.

In particular, the glazing may presents a direct solar transmittance, asdetermined according to the European standard EN 410, which is at least1%, preferably at least 2% lower than a direct solar transmittance of aglazing having a coating with the same layer structure and layerthicknesses as the Ag alloy coating layer, but wherein the functionalmetal Ag alloy coating layer is replaced by an unalloyed Ag functionalmetal layer.

The glazing may present a direct solar reflectance, as determinedaccording to the European standard EN 410, which is higher than a directsolar reflectance of a glazing having a coating with the same layerstructure and layer thicknesses as the Ag alloy coating layer, butwherein the functional metal Ag alloy coating layer is replaced by anunalloyed Ag functional metal layer.

In particular, the glazing may present a direct solar reflectance, asdetermined according to the European standard EN 410, which is at least3%, preferably at least 5% higher than a direct solar reflectance of aglazing having a coating with the same layer structure and layerthicknesses as the Ag alloy coating layer (15), but wherein thefunctional metal Ag alloy coating layer is replaced by an unalloyed Agfunctional metal layer.

The alloying agent concentration may be 0.15-0.35 at. %, 0.35-0.55 at.%, 0.55-0.75 at. %, 0.75-0.95 at. %, 0.95-1.15 at. %, 1.15-1.35 at. % ofthe coating layer, the rest being Ag.

The coating may present an electrical sheet resistance which is lowerthan an electrical sheet resistance of a coating having the same layerstructure and layer thicknesses as the aforementioned coating, butwherein the functional metal Ag alloy coating layer is replaced by anunalloyed Ag functional metal layer.

As will be discussed further on, it is both unexpected and surprisingthat the sheet resistance is particularly low for an alloying agentconcentration in the interval of about 0.15 at. % to 1.35 at. %.

A lower sheet resistance is the equivalent to a lower emissivity or ahigher IR reflectivity, which in turn corresponds to less heat that isallowed to pass through the glass pane, i.e., the glazing has a higherenergy saving potential. A lower sheet resistance may also mean a higherquality of the functional metal layer, which could lead to less lightabsorption within the material and thus higher visible transmittance.

The conductivity of the functional metal layer is directly related toits emissivity, such that a higher conductivity (equivalent to a lowerresistivity) leads to a lower emissivity. A low emissivity is equivalentto a high IR reflectivity. High IR reflectivity is thus the same assaying a low emissivity or a high electrical conductivity. With “high”it is meant a conductivity that is higher than that of an unalloyed Agfunctional metal layer for the same functional metal layer thickness.

By emissitivity of a material means its effectiveness in emitting energyas thermal radiation.

The coating may present an electrical sheet resistance which is at least1%, preferably at least 3%, most preferably at least 5% lower than anelectrical sheet resistance of a coating having the same layer structureand layer thicknesses as the aforementioned coating, but wherein thefunctional metal Ag alloy coating layer is replaced by an unalloyed Agfunctional metal layer.

The coating may further comprise at least two anti-reflective layers,each having at least one dielectric layer, wherein each functional metallayer is sandwiched between two anti-reflective layers.

The coating may further comprise at least one blocker layer locatedimmediately above and in direct contact with the functional metal layer.

The coating may further comprise at least one seed layer locatedimmediately below and in contact with the functional metal layer.

The coating may further comprise at least one diffusion barrier layerlocated immediately on top of the transparent substrate.

The coating may further comprise at least one top layer locatedimmediately onto the outermost anti-reflective layer.

The glazing may further comprise at least one further functional metalAg alloy coating layer. The at least one further functional metal Agalloy coating layer may consist essentially of Ag with an alloying agentselected from a group consisting of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe,Ni, Cu, Zn, Ge, Zr, Nb, Mo, In, Sn, Hf, Ta or W. The alloying agentconcentration of the at least one further functional metal Ag alloycoating layer may be 0.15-1.35 at. %, preferably 0.20-1.00 at. % or0.25-0.80 at. %, the rest being Ag, and the at least one further Agalloy coating layer may have a thickness of 5-20 nm, preferably 8-15 nmor more preferably 8-12 nm.

By at least one further functional metal Ag alloy coating layer is meantthat the the glazing may comprise additional functional metal layers.Typically, such a glazing comprises two or three functional metallayers.

Hence, the alloying agent of the at least one further functional metalAg alloy coating layer may be the same as the alloying agent of thefirst functional metal Ag alloy coating layer. Alternatively, thealloying agent of the at least one further functional metal Ag alloycoating layer and the alloying agent of the first functional metal Agalloy coating layer may be different.

The alloying agent concentration of the at least one further functionalmetal Ag alloy coating layer may be the same as the alloying agentconcentration of the first functional metal Ag alloy coating layer.Alternatively, the alloying agent concentration of the at least onefurther functional metal Ag alloy coating layer and the alloying agentconcentration of the first functional metal Ag alloy coating layer maybe different.

The alloying agent concentration of the at least one further functionalmetal Ag alloy coating layer may be 0.15-0.35 at. %, 0.35-0.55 at. %,0.55-0.750 at. %, 0.75-0.95 at. %, 0.95-1.15 at. %, 1.15-1.35 at. % ofthe functional metal coating layer, the rest being Ag.

The glazing may have a light transmittance of at least 20%, preferablyat least 30% or at least 40% as determined according to the standard EN410.

According to the invention, there is provided a window glass sheetformed by a glazing as described above.

According to the invention, there is provided a vehicle glass sheetformed by a glazing as described above.

According to a second aspect, there is provided a method of producing aglazing in the form of a window glass or vehicle glass. The methodcomprises providing a transparent glass substrate, applying, by PhysicalVapor Deposition, at least one functional metal Ag alloy coating layerto the substrate, such that the Ag alloy coating layer consistsessentially of Ag with an alloying agent selected from a groupconsisting of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Zr, Nb,Mo, In, Sn, Hf, Ta or W. An alloying agent concentration is 0.15-1.35at. %, preferably 0.20-1.00 at. %, more preferably 0.25-0.80 at. % ofthe coating layer, the rest being Ag, and the Ag alloy coating layer hasa thickness of 5-20 nm, preferably 8-15 nm or 8-12 nm.

The alloying agent concentration may be 0.15-0.35 at. %, 0.35-0.55 at.%, 0.55-0.75 at. %, 0.75-0.95 at. %, 0.95-1.15 at. %, 1.15-1.35 at. % ofthe coating layer, the rest being Ag.

The Ag alloy coating layer may, but need not, be deposited directly onthe substrate. Alternatively, there may be one or more additional layersbetween the Ag alloy coating layer and the substrate.

The method may further comprise providing at least two anti-reflectivelayers, each having at least one dielectric layer, such that eachfunctional metal layer is sandwiched between two anti-reflective layers.

The method may further comprise providing at least one blocker layerimmediately above and in direct contact with the functional metal layer.

The method may further comprise providing at least one seed layerimmediately below and in contact with the functional metal layer.

The method may further comprise providing at least one diffusion barrierlayer immediately on top of the transparent substrate.

The method may further comprise providing at least one top layerimmediately onto the outermost anti-reflective layer.

The additional layers, such as anti-reflective layers, blocker layer,seed layer, diffusion barrier layer and top layer may be deposited byPhysical Vapor Deposition (PVD).

The Ag alloy coating layer may be deposited from a Ag alloy sputteringtarget.

There is provided a sputtering target which may comprise a homogeneousbody of Ag alloy target material. The Ag alloy target material consistsessentially of Ag with an alloying agent selected from a groupconsisting of Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ge, Zr, Nb,Mo, In, Sn, Hf, Ta or W. An alloying agent concentration is 0.15-1.35at. %, preferably 0.20-1.00 at. % or 0.25-0.80 at. % of the Ag alloycoating layer, the rest being Ag.

The concentrations specified for the Ag alloy coating layer apply to thesputter target as well.

According to a third aspect, there is provided use of the Ag alloysputter target as described above for applying a surface coating on atransparent glass substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example of a glazing structure.

FIG. 2 illustrates the relation between the sheet resistance and thethickness of unalloyed Ag functional metal layers and Al-alloyed Agfunctional metal layers, respectively.

FIG. 3a and FIG. 3b illustrate the relation between the sheet resistanceand the Al concentration of Al-alloyed Ag functional metal layers forhigh and low Al concentrations, respectively.

FIG. 4a illustrates the transmittance at different wavelengths ofunalloyed Ag functional metal layers and Al-alloyed Ag functional metallayers having different thicknesses, respectively.

FIG. 4b illustrates the reflectance at different wavelengths ofunalloyed Ag functional metal layers and Al-alloyed Ag functional metallayers having different thicknesses, respectively.

DETAILED DESCRIPTION

The concept disclosed herein will now be explained in more detail.Initially, the structure of a glazing is described, thereafter themethod of producing such a glazing is described. Finally,characterization results of the glazing are discussed.

In FIG. 1 a non-limiting example of a structure of a glazing 1 isschematically illustrated. When viewed from the bottom to the top, theglazing 1 comprises a transparent substrate 11 and a coating 10comprising multiple layers of thin film materials. The coating 10comprises an optional diffusion barrier layer 12, an antireflectivelayer 13, an optional seed layer 14, a functional metal layer 15, anoptional blocker layer 16, an antireflective layer 17 and an optionaltop layer 18.

The transparent substrate 11 may be a glass substrate, such as asoda-lime glass substrate, or a substrate of organic polymers. Thesubstrate may be homogeneous or laminated, comprising one or more glasslayers and, e.g., one or more polymer films. Preferably, an outwardlyexposed surface, on which the coating is deposited, is made of glass.

The dimension of the transparent substrate 11 may range from over-sizedglass panes, which, e.g., may be 3300×6000 mm or 3210×15000 mm orlarger, down to small structures, e.g., 20033 200 mm. The describedglazing is, however, not limited to any specific size of the substrate.

The thickness of the transparent substrate may be about 0.4 mm to 25 mm,or about 2 mm to 8 mm or 4 mm to 6 mm. The described coating is,however, not limited to any thickness of the substrate 11.

An optional diffusion barrier layer 12 may be formed on the transparentsubstrate 11. The diffusion barrier layer may be a layer of Al₂O₃ orzinc stannate.

The diffusion barrier layer 12 may act as a barrier layer and thepurpose of the diffusion barrier layer is to prevent Na ions fromdiffusing from the glass into the other layers, such as the functionalmetal layer, of the structure. Diffusion into the functional metal layer15 may have detrimental effects on said layer.

The anti-reflective layer 13 may be formed either directly on thetransparent substrate 11 or on the optional diffusion barrier layer 12.

The anti-reflective layer 13 may comprise at least one dielectric layerof a metal oxide, such as tin oxide, zinc oxide, zinc tin oxide,titanium oxide, silicon oxide, niobium oxide or zirconium oxide, or ametal nitride, such as silicon nitride or titanium nitride.

The purpose of the anti-reflective layer 13 is to tune the opticalproperties of the glazing 1 by tailoring the refractive index of thedielectric layers. The anti-reflective layer 13 may also protect thefunctional layer 15 from chemical attack and/or mechanical stress.

The thickness of the anti-reflective layer 13 may be about 5 to 120 nm,or about 15 to 100 nm, or about 20 nm to 90 nm.

On top of the antireflective layer 13, a seed layer 14 may be formed.The seed layer 14 may be a layer of zinc oxide or zinc oxide doped by anadditional element, such as Al.

The purpose of the seed layer 14 is to improve the quality of thefunctional metal layer 15. For example, it may impose an epitaxialrelationship for the functional metal layer 15 so that the crystallitesin the functional metal layer 15 favour to grow with a (111)out-of-plane oriented texture and in that way increases conductivity ofthe functional metal layer 15.

The thickness of the seed layer 14 may be about 5 to 25 nm, or about 6to 15 nm. The functional metal layer 15 may be formed onto the seedlayer 14 or directly on the anti-reflective layer 13.

The functional metal layer 15 is Ag alloyed with Mg, Al, Si, Ca, Ti, V,Cr, Mn, Fe, Ni, Cu, Zn, Ge, Zr, Nb, Mo, In, Sn, Hf, Ta or W. Thefunctional metal layer may have high IR reflectivity characteristics.

The purpose of the functional metal layer 15 is to reduce the heattransfer through the glazing, while still being transparent in thevisible spectrum.

The thickness of the functional layer 15 may be about 5 to 20 nm, orabout 8 to 15 nm, or about 8 nm to 12 nm.

The structure 1 may further comprise an optional blocker layer 16 formedon top of the functional metal layer 15.

The blocker layer 16 may be an oxidized metal layer, based on nickelchrome, nickel, chrome, niobium, titanium or zinc, or a metal nitridelayer, based on nickel chrome or chrome.

The purpose of the blocker layer 16 is to improve the quality of thefunctional metal layer 15 by protecting the functional metal layerduring deposition of a subsequent layer, such as the anti-reflectivelayer 17.

The thickness of the blocker layer 16 may be about 0.5 to 4 nm, or about0.5 to 2 nm.

The antireflective layer 17 may then be formed on the blocker layer 16or directly on the functional metal layer 15. The antireflective layer17 may comprise at least one dielectric layer.

The purpose of the antireflective layer 17 is to tune the opticalproperties of the glazing 1 by tailoring the refractive index of thedielectric layers.

The anti-reflective layer 17 may also protect the functional layer 15from chemical attack and/or mechanical stress.

The thickness of the anti-reflective layer 17 may be about 5 to 120 nm,or about 15 to 100 nm, or about 20 nm to 90 nm.

A top layer 18 may be formed on the antireflective layer 17.

The top layer 18 may comprise a nitride, e.g., silicon nitride, or anoxide, e.g., aluminum oxide or titanium oxide.

The purpose of the top layer 18 is to protect the underlying layers frommechanical damage, e.g., scratches, and chemical attacks.

The coating 10 may be used as a so-called low-emissivity coating or as aso-called solar control coating. The emissivity of such a coating istypically 0.10, preferably ≤0.07.

The main purpose of a low-emissivity coating is to reflect heat (longwavelength IR radiation, such as 5-50 μm) back into the interior of,e.g., a building such that the heat is not lost to the outside of thebuilding.

The main purpose of a solar control coating is to reflect solar heat(near wavelength IR radiation, such as 780-2500 nm) such that theinterior of, e.g., a building or a vehicle is not heated by the sun.

For a low-emissivity coating, typically only one single functional metallayer 15 sandwiched between two anti-reflective layers, together withoptional layers discussed above, is formed on the substrate, such as aglass pane, thus forming a glazing.

For a solar control coating, two or three of the functional metal layersmay be combined in a coating layer structure to form a glazing.Excluding the optional layers, the layer structure of a glazingcomprising two functional metal layers may be glass/anti-reflectivelayer/functional metal layer/anti-reflective layer/functional metallayer/anti-reflective layer. A layer structure of a glazing comprisingthree functional metal layers may be glass/anti-reflectivelayer/functional metal layer/anti-reflective layer/functional metallayer/anti-reflective layer/functional metal layer/anti-reflectivelayer.

Method for Production of the Glazing

Each of the layers of the coating 10 in FIG. 1 is formed by PhysicalVapor Deposition (PVD), such as magnetron sputtering, evaporation, arcevaporation, pulsed laser deposition and combinations thereof.Preferably, the layers are deposited by magnetron sputtering.

The layers of the coating 10 may be deposited one layer at a time.

The different layers may be deposited in the same or in differentsputter zones. The sputter zones may be spatially separated.

Alternatively, the sputter zones may be completely or partiallyoverlapping sputtering zones.

The sputter zones may be stationary and the transparent substrate may bemoveable. The transparent substrate may be passed through a sputter zoneor between successive sputter zones by means of translation, and/orrotation of the substrate in relation to the sputter zones.

Alternatively, the substrate may be stationary and the sputter zones maysurround and face, or at least partially face, the stationary substrate.

The dimensions of the sputtering zones may depend on the application andon the size of the substrate to be coated.

The deposition sources may be so-called sputtering targets.

There may be different deposition sources used for each deposited layer.Alternatively, the same deposition source may be used for deposition ofa number of different layers.

The functional metal layer may be deposited from one single depositionsource, such as an alloy sputtering target. Alternatively, thefunctional metal layer is deposited from two separate depositionsources. For example, there may be one deposition source providing theAg and one deposition source providing the alloying agent. If thefunctional metal layer is deposited from separate deposition sources,the deposition of Ag and the alloying agent may take placesimultaneously.

Each of the deposited layers may, but need not, form a continuous layeronto the previous layer or onto the substrate.

Prior to deposition of the functional metal layer 15, additional layersmay be deposited onto the substrate. Examples of such layers are adiffusion barrier layer 12, an anti-reflective layer 13 and/or a seedlayer 14.

Additional layers may be deposited onto the functional metal layer 15.Examples of such layers are a blocker layer 16, an anti-reflective layer17 and/or a top layer 18.

As an example, for deposition of the functional metal layer, the PVDsystem in which the deposition of layers take place may have a basepressure of about 10⁻² Pa or below. A typical pressure in the PVD systemwhen using a sputtering gas, such as Ar, is typically in the range of0.1 to 2 Pa.

Typically, the substrate is not intentionally heated during depositionof the layers of the coating.

Characterization Results of the Glazing

FIG. 2 shows the sheet resistance as a function of the functional metallayer thickness of a glazing comprising an unalloyed Ag functional metallayer and a silver aluminum alloy functional metal layer (0.46 at. %Al), respectively. As can be seen, the sheet resistance of the glazingcomprising the silver aluminum alloy functional metal layer is lower ascompared to the unalloyed Ag metal functional layer for all thicknesses.A lower sheet resistance for the same layer thickness is equivalent to alower emissivity and a higher IR reflectivity, which in turn correspondsto a lower heat transfer through the glazing, i.e., the glazing has ahigher energy saving potential. In addition, a lower sheet resistancemay mean a higher quality of the functional metal layer, which may leadto less light absorption within the function metal layer and thus ahigher transmittance of visible light. In FIG. 3a and FIG. 3b , thesheet resistance of silver aluminum alloy functional metal layers with athickness of 10 nm is shown for different Al concentrations. FIG. 3ashows the sheet resistance for Al concentrations ranging from 1.5 at. %to 7.5 at. %, while FIG. 3b shows the sheet resistance for Alconcentrations ranging from 0.2 at. % to 0.9 at. %. As can be seen inFIG. 3b , the sheet resistance is lower for silver aluminum alloyfunctional metal layers with an Al concentration of 0.29 to 0.77 at. %as compared to an unalloyed Ag functional metal layer. For higher Alconcentrations, from about 2 to 7 at. % of the functional metal layer,the sheet resistance is significantly higher as compared to an unalloyedAg functional metal layer, see FIG. 3 a.

It is unexpected and surprising that the sheet resistance is very low inthe alloying agent concentration interval of about 0.15 to 1.35 at. %.As seen in FIG. 3a it is expected that there is a linear relationshipbetween increasing Al concentration and increasing sheet resistance.However, unexpectedly there is a minimum sheet resistance at an alloyingagent concentration of about 0.5 at. % as shown in FIG. 3b . In theprior art documents found, 0.1 to about 10 at. %, or higher, alloyingagent concentrations is typically shown.

FIG. 4a shows the transmittance of glazings comprising a silver aluminumalloy functional metal layer and an unalloyed Ag layer, respectively, ofdifferent thicknesses. Results from functional layers of differentthicknesses are included to show that the effect is applicable to morethan one thickness. As illustrated in FIG. 4a , the transmittance of theglazings are high in the visible spectrum, such as 380 to 780 nmwavelengths, while being significantly lower in the near-IR part of thespectrum, such as 780 to 2500 nm. If comparing the transmittance ofunalloyed Ag and silver aluminum alloy functional metal layers of thesame thicknesses it can be seen that the silver aluminum alloyfunctional metal layers exhibit a lower transmittance in the near-IRregion and at the same time that the maximum transmittance of the silveraluminum alloy functional metal layers is higher in the visible region.

FIG. 4b shows the reflectance of glazings comprising a silver aluminumalloy functional metal layer and an unalloyed Ag layer, respectively, ofdifferent thicknesses. Results from functional layers of differentthicknesses are included to show that the effect is applicable to morethan one thickness.

The lower transmittance of the silver aluminum alloy functional metallayers as compared to the unalloyed Ag layers in the near-IR regionshown in FIG. 4a is due to a higher reflectance in this region, as seenin FIG. 4 b.

Ag is known to nucleate three-dimensional atomic islands when grown onweakly bonding surfaces, such as commonly used oxide or nitride layersdeposited prior to the functional metal layer. A hypothesis is that byadding an alloying agent that is more prone to bond to an oxide/nitridethan Ag (i.e., the bond strength of alloying agent to oxide/nitride isgreater than the bond strength of Ag to oxide/nitride), the alloyingagent may promote lateral over vertical island growth. This reduces theaspect ratio of the islands and lowers overall surface roughness ascompared to the growth of an unalloyed Ag layer, yielding a morphologyimprovement beneficial for higher conductivity. In addition, a morepreferential bonding to oxides/nitrides of the alloying agent ascompared to between alloying agent and Ag (i.e., a more favorableenthalpy of mixing of the alloying agent-oxide/nitride than the enthalpyof mixing of alloying agent-Ag) also provides a driving force foralloying agents to diffuse towards the oxides/nitrides. This effectivelylowers the alloying agent concentration within the crystallites, causingless electron scattering inside the crystallites and hence an increasedconductivity. The alloying agent concentratration thus needs to beselected within a range that is high enough to positively affect themorphology, while still being low enough to minimize electron scatteringinside the crystallites.

Experimental Details

Coatings, comprising multiple thin layers, were deposited by means ofmagnetron sputtering on 100×100 mm² glass substrates in an inlinecoater. Two different deposition series were produced, one where thealloying agent (in this example Al) concentration of the functionalmetal Ag alloy coating layer was varied at a constant metal layerthickness of 10 nm and one where the alloying agent (in this example Al)concentration of the functional metal Ag layer was held constant at 0.46at. % for different functional metal layer thicknesses. For reference,unalloyed Ag functional metal layers were also deposited at otherwisethe same process conditions. The deposition sequence was initiated byfirst depositing a 7 nm thick dielectric layer consisting of ZnO:Al (2wt. % Al), after which the functional metal coating layer was deposited.On top of this, a 1.6 nm thick blocker layer consisting ofsub-stoichiometric ZnO:Al (2 wt. % Al) was deposited prior to thedeposition of a 35 nm thick dielectric layer consisting of ZnO:Al (2 wt.% Al).

The electrical properties of the coatings were measured using a 4-pointprobe to determine the sheet resistance. The optical properties in termsof transmittance and reflectance of the glazing were measured with anUV/VIS/NIR spectrophotometer in the wavelength range 250-2500 nm.

The alloying agent concentration of the functional metal layer wasdetermined using wavelength dispersive X-ray spectroscopy measurementsof about 200 nm thick functional metal layers deposited directly onsilicon substrates without the deposition of any other layers.

1. Glazing in the form of a window glass or vehicle glass, comprising: atransparent glass substrate, and a coating, comprising at least onefunctional metal Ag alloy coating layer, wherein the Ag alloy coatinglayer consists essentially of Ag with an alloying agent being Al,wherein the alloying agent is present in a concentration of 0.15-1.35at. % of the Ag alloy coating layer, the rest being Ag, and wherein theAg alloy coating layer has a thickness of 5-20 nm.
 2. The glazing asclaimed in claim 1, wherein the alloying agent is present in aconcentration selected from the group consisting of 0.15-0.35 at. %,0.35-0.55 at. %, 0.55-0.75 at. %, 0.75-0.95 at. %, 0.95-1.15 at. %, and1.15-1.35 at. % of the Ag alloy coating layer, the rest being Ag.
 3. Theglazing as claimed in claim 1, wherein the coating presents anelectrical sheet resistance which is lower than an electrical sheetresistance of a comparative coating having the same layer structure andlayer thicknesses as the coating, wherein in the comparative coating,the Ag alloy coating layer is replaced by an unalloyed Ag functionalmetal layer.
 4. (canceled)
 5. The glazing as claimed in claim 1, whereinthe glazing presents a direct solar transmittance, as determinedaccording to the European standard EN 410, which is lower than a directsolar transmittance of a glazing having a comparative coating with thesame layer structure and layer thicknesses as the Ag alloy coatinglayer, wherein in the comparative coating, the Ag alloy coating layer isreplaced by an unalloyed Ag functional metal layer.
 6. (canceled)
 7. Theglazing as claimed in claim 1, wherein the glazing presents a directsolar reflectance, as determined according to the European standard EN410, which is higher than a direct solar reflectance of a glazing havinga comparative coating with the same layer structure and layerthicknesses as the Ag alloy coating layer, wherein in the comparativecoating, the Ag alloy coating layer is replaced by an unalloyed Agfunctional metal layer.
 8. (canceled)
 9. The glazing as claimed in claim1, wherein the coating further comprises at least two anti-reflectivelayers, each having at least one dielectric layer, wherein each Ag alloycoating layer is sandwiched between two anti-reflective layers.
 10. Theglazing as claimed in claim 1, wherein the coating further comprises atleast one blocker layer located immediately above and in direct contactwith the Ag alloy coating layer.
 11. The glazing as claimed in claim 1,wherein the coating further comprises at least one seed layer locatedimmediately below and in contact with the Ag alloy coating layer. 12.The glazing as claimed in claim 1, wherein the coating further comprisesat least one diffusion barrier layer located immediately on top of thetransparent glass substrate.
 13. The glazing as claimed in claim 9,wherein the coating further comprises at least one top layer locatedimmediately onto the outermost anti-reflective layer.
 14. The glazing asclaimed in claim 1, further comprising at least one further functionalmetal Ag alloy coating layer, wherein the at least one further Ag alloycoating layer consists essentially of Ag with an alloying agent beingAl, wherein the alloying agent is present in a concentration of0.15-1.35 at. % of the at least one further Ag alloy coating layer, therest being Ag, and wherein the at least one further Ag alloy coatinglayer has a thickness of 5-20 nm.
 15. (canceled)
 16. The glazing asclaimed in claim 1, wherein the glazing has a light transmittance of atleast 20% as determined according to the standard EN
 410. 17. A methodof producing a glazing in the form of window glass or vehicle glass,comprising: providing a transparent glass substrate, applying, byPhysical Vapor Deposition, at least one functional metal Ag alloycoating layer to the substrate, such that the Ag alloy coating layerconsists essentially of Ag with an alloying agent being Al, wherein thealloying agent is present in a concentration of 0.15-1.35 at. %, of thecoating layer, the rest being Ag, and the Ag alloy coating layer has athickness of 5-20 nm.
 18. The method as claimed in claim 17, wherein thealloying agent is present in a concentration selected from the groupconsisting of 0.15-0.35 at. %, 0.35-0.55 at. %, 0.55-0.75 at. %,0.75-0.95 at. %, 0.95-1.15 at. %, and 1.15-1.35 at. % of the Ag alloycoating layer, the rest being Ag.
 19. The method as claimed in claim 17,wherein the method further comprises providing at least twoanti-reflective layers, each having at least one dielectric layer, suchthat each Ag alloy coating layer is sandwiched between twoanti-reflective layers.
 20. The method claimed in claim 17, wherein themethod further comprises providing at least one blocker layerimmediately above and in direct contact with the Ag alloy coating layer.21. The method as claimed in claim 17, wherein the method furthercomprises providing at least one seed layer immediately below and incontact with the Ag alloy coating layer.
 22. The method as claimed inclaim 17, wherein the method further comprises providing at least onediffusion barrier layer immediately on top of the transparent glasssubstrate.
 23. The method as claimed in claim 19, wherein the methodfurther comprises providing at least one top layer immediately onto theoutermost anti-reflective layer.
 24. The method of producing a glazingas claimed in claim 17 wherein the functional metal Ag alloy coatinglayer is deposited from an Ag alloy sputtering target, wherein the Agalloy sputtering target consists essentially of Ag with an alloying wentbeing Al, wherein the alloying went is present in a concentration of0.15-1.35 at. % of the Ag alloy sputtering target, the rest being Ag.25-26. (canceled)